One proposed suspension device of this type comprises a fin pierced by holes of slightly larger diameter than the diameter of the tubes to be supported and at the same pitch as the tubes of the bundle. Thus, each vertical tube includes a kind of half-fin which is fixed to the half-fin of the other vertical tube by bridges disposed between successive horizontal tubes of the bundle, but the mid portions of the bridges which are in contact with the high temperature horizontal tubes and which are relatively far away from the two vertical tubes are poorly cooled by conduction. The bridges formed between the vertical tubes oxidize or rust rapidly because of their high temperature in gases which are often corrosive. Furthermore, this device is only applicable to single loop heat exchangers since it would otherwise be impossible to thread the tubes individually through the holes in the fin.
Proposals have also been made to weld saddles between the horizontal tubes of the bundle and the vertical load-bearing tubes. The saddles are close enough to the vertical tubes to be properly cooled by conduction, but the tubes of the bundle are rigidly connected thereto which gives rise to large stresses due to thermal expansion or to vibration, and these can lead to cracks in the welds.
Proposals have also been made to weld flats between two adjacent parallel vertical tubes. However, these flats are too big and suffer from the problem mentioned above concerning the fin pierced by holes. The middle portions of the flats are poorly cooled by conduction and are thus subjected to excessive temperatures which can lead to their destruction by oxidation or corrosion.
Finally, U.S. Pat. No. 3,267,913 proposes a suspension device comprising pairs of vertical tubes fitted with half-fins including circular notches for housing the horizontal tubes and separated by un-notched zones. The horizontal tubes are welded to the notches and come into contact with the vertical tubes. The connection between the horizontal tubes and the vertical tubes is thus rigid, thereby leading to high stresses due to thermal expansions and to vibration as mentioned above.
Preferred embodiments of the present invention provide a suspension device which does not include a poorly cooled zone, and which is thus less exposed to corrosion, and which is not rigidly fixed to the tubes of the heat exchanger so as to avoid weld cracking due the effects of thermal stresses or vibration.